Drug Reactions Flashcards
What is morbilliform? Drugs causing?
Commonest drug reaction
Presenting with generalised erythematous macule and papules e.g. on the trunk ± mild fever, within 1-3 weeks of drug exposure
No mucosa involvement
Drugs: Amoxicillin Cephalosporins AEDs Sulphonamides Allopurinol Thiazides
Ddx:
Measles
Describe urticaria. Drugs. Mx.
Itchy erythematous wheals that move around appear rapidly after drug exposure ± angio-oedema/anaphylaxis
IgE mediated
Penicillins Cephalosporins Opiates NSAIDs ACEi Thiazides Phenytoin
Antihistamine ± IV hydrocoritsone/IM adrenaline if anaphylaxis
What is erythroderma? Causes?
More than 90% of body skin is involved in a rash any kind
Widespread erythema
Causes: Eczema Psoraisis Drugs: sulphonamides, allopurinol, carbemazepine, gold Lymphomas Leukaemia
What is Steven-Johnson syndrome? Signs? Causes?
Vague upper respiratory tract symptoms occur 2-3 weeks after starting a drug and 2 days before a rash that affects <10% of body surface.
Painful erythematous macules evolving to form target lesions
Severe mucosal ulceration of 2 or more surfaces
E.g. conjunctivae, oral cavity, labia, urethra
Drugs:
Sulphonamides, AEDs, penicillins, NSAIDs
What is toxic epidermal necrolysis? Signs?
Flu like symptoms may precede skin involvement
>30% of body surface
Widespread painful dusky erythema, then necrosis of large sheets of epidermis
Mucosae severely affected
Positive Nikolsky’s sign epidermis separates with mild lateral pressure
What drugs can cause TEN?
Phenytoin Sulphonamides Allopurinol Penicillins Carbemazepine NSAIDs
What is Nikolsky’s sign?
Positive Nikolsky’s sign epidermis separates with mild lateral pressure
in TEN
What is management for SJS/TEN?
Stop precipitating factor Supportive care, manage in ICU, HDU IV immunoglobulin is effective Avoid systemic steroids - increased risk fo infection Relieve pain Protect skin
What is lichenoid?
Similar to lichen plants
Itchy flay topped purple-red papules
Beta blockers
Thiazides
Gold
Antimalarials
Topical steroids
What are principles of management of drug reactions?
History of onset and duration of rash Record all DHx Stop the likely offender Document sign and symptoms Mucosal/systemic involvement? Regular emollients for dryness or itch Potent topical steroids reduce itch in widespread mobilliform, eczemaroud or lichenoid reaction.
